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From: ornitz@kodak.UUCP
Newsgroups: sci.research
Subject: Re: Microwave power beaming
Message-ID: <868@kodak.UUCP>
Date: Tue, 2-Jun-87 10:29:08 EDT
Article-I.D.: kodak.868
Posted: Tue Jun  2 10:29:08 1987
Date-Received: Thu, 4-Jun-87 05:23:29 EDT
References: <6693@allegra.UUCP> <1115@oliveb.UUCP> <5893@brl-smoke.ARPA> <1266@ssc-vax.UUCP> <5934@brl-smoke.ARPA>
Reply-To: ornitz@kodak.UUCP (barry ornitz)
Organization: Eastman Kodak Co, Rochester, NY
Lines: 39
Keywords: microwaves, standards, radiation, ANSI
Summary: Microwave Exposure Standards

In article <5934@brl-smoke.ARPA> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes:
>In article <1266@ssc-vax.UUCP> eder@ssc-vax.UUCP (Dani Eder) writes:
>>...  At least in the space-based power
>>supply scenario we looked at, the maximum beam intensity was required
>>to be no more than 300 watts per square meter.  This is 30% of peak
>>desert noonday sunlight intensity. ...
>
>Assuming all that's correct, is 300W/m^2 a safe dosage for microwaves?
>They have considerably different frequency than sunlight, so the body's
>response to them would be via different mechanisms.  In particular I
>suspect that might be enough to cause corneal damage within a short
>amount of time.
>
>Could somebody with microwave safety information check this?

The current ANSI standard for microwave exposure is 5 milliwatts per square
centimeter in the frequency range of 1.5 to 100 GHz.  This works out to 50
watts per square meter which is less than the 300 w/m**2 listed for sunlight.
For frequencies in the range of 300 to 1500 MHz, the maximum power density
for human exposure is f/300 mW/cm**2 where f is the frequency in megaHertz.
These limits may be exceeded if the exposure conditions can be shown by
laboratory procedures to produce specific absorption rates of less than 
0.4 W/kg averaged over the whole body and spatial peak values below 8 W/kg
over any one gram of tissue.  These values are all time averaged over a six
minute period.  Consult ANSI Standard C95.1-1982 for more details.  You are
correct about cornea damage; because the cornea cannot dissipate heat like
the rest of the body, it is the most sensitive organ to microwave energy.

                                            Barry

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|  ___  ________  |
| |  / /        | |  Dr. Barry L. Ornitz   UUCP:...!rochester!kodak!ornitz
| | / /         | |  Eastman Kodak Company
| |< < K O D A K| |  Eastman Chemicals Division Research Laboratories
| | \ \         | |  P. O. Box 1972
| |__\ \________| |  Kingsport, TN  37662       615/229-4904

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